Cross β‐sheet structure formation and abnormal aggregation of proteins are thought to be pathological characteristics of some neurodegenerative disorders. To investigate the novel structural transformation and aggregation, the solid‐state secondary structures of some proteins and peptides associated in thin films were determined by circular dichroism spectroscopy. Insulin, lysozyme, DsbA protein, luciferase, and ovalbumin peptide fall into one group; they show no or slight structural rearrangement from solution to the solid state. Another group, including bovine serum albumin, ovalbumin, α‐synuclein, and plasminogen activator inhibitor‐1 (PAIRC) peptide, undergo structural transformation with an increase of β‐sheet structure in the solid state. The β‐sheet formation of PAIRC peptide may reflect the structural transformation of the serpin reactive center that is relevant to the inhibitor activity. The β‐sheet structure of α‐synuclein in the solid state may correspond to the amyloid‐like aggregates, which are implicated in the pathogenesis of some neurodegenerative diseases. © 2000 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 15–21, 2001

Surface electronic structure in transition-metal (Cr and Mn) doped GaAs (001) studied by in situ photoemission spectroscopy Appl.In order to verify the actual effect of an exponential-doping structure on cathode performance, an exponential-doping structure has been applied to the preparation of the transmission-mode GaAs photocathode via molecular beam epitaxy technique. Compared with the uniform-doping photocathode, the activation and spectral response results show that the exponential-doping photocathode can achieve a higher photoemission capability. In addition, based on the revised uniform-doping and exponential-doping transmission-mode quantum yield equations, the cathode performance parameters such as electron average transport length and electron escape probability of the exponential-doping photocathode are obtained, which are greater than those of the uniform-doping one. The improvement in the cathode performance is attributed to the built-in electric field arising from this special doping structure, which effectively increases the electron transport efficiency and escape probability.

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